Bump webpacker from 4.2.0 to 4.2.2

Bumps [webpacker](https://github.com/rails/webpacker) from 4.2.0 to 4.2.2.
- [Release notes](https://github.com/rails/webpacker/releases)
- [Changelog](https://github.com/rails/webpacker/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rails/webpacker/compare/v4.2.0...v4.2.2)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Gemfile.lock

@@ -86,7 +86,7 @@ GEM
       msgpack (~> 1.0)
     bootstrap-will_paginate (1.0.0)
       will_paginate
-    builder (3.2.3)
+    builder (3.2.4)
     bunny (2.14.3)
       amq-protocol (~> 2.3, >= 2.3.0)
     byebug (11.0.1)
@@ -398,7 +398,7 @@ GEM
       net-ssh (>= 2.8.0)
     structured_warnings (0.4.0)
     temple (0.8.2)
-    thor (0.20.3)
+    thor (1.0.1)
     thread_safe (0.3.6)
     tilt (2.0.10)
     turbolinks (5.2.1)
@@ -421,7 +421,7 @@ GEM
       addressable (>= 2.3.6)
       crack (>= 0.3.2)
       hashdiff (>= 0.4.0, < 2.0.0)
-    webpacker (4.2.0)
+    webpacker (4.2.2)
       activesupport (>= 4.2)
       rack-proxy (>= 0.6.1)
       railties (>= 4.2)